Insert sheets (or insert films) refer to sheets or films that are applied to a surface of a molded product in insert molding or injection molding to provide a variety of decorative effects. Examples of insert sheets include sheets for decorating molded products simultaneously with molding, such as a sheet for decorating a molded product simultaneously with injection molding, which can form a decorative layer on a surface of a molded product simultaneously with insert or injection molding. The insert sheets are used for a wide range of applications, including auto interior materials (e.g., a center fascia, window switch, and console box), auto exterior materials (e.g., a mirror housing, side molding and bumper cap), housings for electric home appliances, electronic devices (e.g., a mobile phone and a notebook computer), and the like.
Typically, an insert sheet is formed with a decorative layer, which can realize a metallic appearance with a variety of patterns, by various processes, such as gravure printing. However, the decorative layer formed by the existing process has problems of significantly inferior adhesion to actual metal (for example, chrome and stainless steel), artificial appearance, and the like.
Accordingly, an attempt has recently been made to realize a variety of metallic appearances through a metal deposition process such as vacuum deposition or the like. However, a metal deposition layer formed by vacuum deposition has a problem in that the insert sheet including the metal deposition layer suffers from deterioration of endurance or the like due to low adhesion between the decorative layer and an adherent, that is, a synthetic resin substrate. Another problem with the conventional process is that the properties of the insert sheet such as surface endurance and formability are not satisfactory, uniformity of the metal deposition layer is low, and the deposition layer may be cracked in the process of molding.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.